I’m a native of the Chicago area: I grew up in the Southwest suburbs, and my family came from the South Side of Chicago proper. After college I lived on the North Side, and my friends and twin brother still live there, scattered around various parts of the city.

Because of my own personal history with the city, as well as my personal network in the area, I like to think that I know Chicago well. I definitely have a ‘feel’ for different neighborhoods: which areas have which characteristics.

Specific to safety and crime, I’ve always had a vague sense of “this neighborhood is safe” or “that neighborhood is rough.” To be honest though, my understanding of neighborhood-to-neighborhood differences has been just that: vague.

Even with a lifetime of experience in and around the city, and a personal network of 50-100 people that extends all over the Chicago area, I’ve only had a vague sense of the differences between different neighborhoods.

But a couple of weeks ago, I rapidly increased my depth of knowledge using data. I downloaded about 10 years of crime data from data.cityofchicago.org.

Using the right geospatial visualization technique, in 1 day I revealed patterns that have been hidden from me for a lifetime.

2001-2013 Data source: data.cityofchicago.org

Data source: data.cityofchicago.org

That is the power of visualization. If you’re doing it right, you can rapidly gain deep insight into things that would otherwise remain hidden.